GROUP STUDY ACOUSTICS

An acoustical phenomenon wherein the sound continues to persist after the cause of sound has stopped resulting in repeated reflections is calledEcho b. reverberation c. reflection d. diffractionA group of filters has 1/3 octave of spacing. If the initial frequency is 25 Hz, what is the next frequency available for the filter?50 Hz b. 12.5 Hz c. 75 Hz d. 31.5 HzA type of microphone that uses the principle of a capacitor as a means of transduction. It uses a polarizing voltage of between 9 and 48 V of DC supply applied to its diaphragm by an external power supply.Dynamic b. condenser c. ribbon d. carbonDetermine the sound power in Watts produced by the banks alarm if a by-stander heard the alarm at a sound pressure level of 100 dB-SPL. The by-stander is 100 ft away from the bank.56.85 w b. 55.68w c. 58.56 w d. 58.65wA loudspeaker produces an SPL of 85dB-SPL at 1 meter distance and input electrical power of 1 W. How loud is the SPL at distance of 20 meters if this speaker is driven to 10 W of electrical power?82 dB SPL b. 69 dB SPL c. 65 dB SPL d. 79 dB SPLA number from 0 to 1 representing the ability of a surface material to absorb sound energy is known asSound absorption b. reflection coefficient c. absorption coefficient d. room constantThe difference in dB between the loudest level of sound and the softest passage of sound is known as _Headroom b. S/N c. gain d. dynamic rangeHow many octaves is the frequency range 1 to 8MHz? How much acoustic power must a public address system be able to put out in order to create an SPL

of 100 dB for a musical show in the 10,000 cubic meter auditorium?

a. 30 mW b. 200 W c. 33 W d. 80W

• For a music lover concert A is 440 Hz. If a musical note one octave higher were played, it would be

______ that frequency.

a. One-half b. One-fourth c. Double d. Triple

• In a 220 Hz synthesizer signal, if a note were played one octave below it would be _______.

a. 22 Hz b. 27.5 Hz c. 440 Hz d. 110 Hz

• Designates the sensation of low or high in the sense of the base and treble.

a. SPL b. Pitch c. Frequency d. Intensity

• Sound intensity is given as:

a. df / dP b. dP / dA c. dE / dP d. dA / dP

• A method of expressing the amplitude of complex non-periodic signals such as speech.

a. volume b. frequency c. pitch d. wavelength

• A large speaker having a large diameter (15 cm and above).

a. tweeter b. triaxial speaker c. coaxial speaker d. woofer

• What do you call of a sound transducer that uses a polarizing potential and depends upon

capacitance variation for generation of a corresponding potential difference?

a. electrostatic b. electroacoustic c. electrodynamic d. electromagnetic

• A special type of electrostatic microphone which holds polarization indefinitely without continued application of a polarizing potential.

a. condenser b. capacitive microphone c. electret d. all of the above

• Sound transducer whose output potential is generated through the flexing of crystalline

elements as it is acted by sound waves.

a. piezoelectric b. electroacoustic c. electrodynamic d. electromagnetic

• An electroacoustic transducer that radiates acoustic power into the air. The acoustic

waveform is equivalent to the electrical input wavefrom.

a. electrets b. diaphragm c. piezoelectric d. loudspeaker

• A dome over a stadium has a diameter of 100 m and an area of 104 m2. If the average intensity of sound passing outward of through this surface is 10-3 W/m2, the total power is about

a. 20W b. 10W c. 30W d. 40W

• Sound intensity level is given by: in dB:

a. 10 log I/Iref b. 20 log I/Iref c. 10 log Pref/Iref d. 20 log Iref/Pref

• The reference intensity for sound in air is:

a. 10 10 W/m2 b. 10 12 W/m2 c. 10 16 W/m2 d. 10 13 W/m2

• The intensity of sound which is 10-3 W/m2 in dB

a. 90 b. 80 c. 70 d. 60

• Sound pressure level in dB is:

a. 20 log P/Pref b. 10 log P/Pref c. 10 log P/ref/P d. 10 log I/Iref

• Pressure amplitude reference level of sound in air:

a. 20 millipascal b. 20 micropascal c. 30 micropascal d. 40 micropascal

• A sound pressure amplitude level of 0.4 Pa corresponds to a sound pressure level in dB equal to:

a. 26 b. 40 c. 86 d. 56

• An SPL of 58 dB means:

a. 0.15 Pa b. 0.016 Pa c. 1.8 Pa d. 2 Pa

• The lowest frequency produced by an instrument.

a. Harmonic b. Fundamental c. Midrange d. 0 Hz

• _____ is the range of quietness to loudness.

a. Static Range b. Dynamic Range c. Flat Response d. Active Response

• How many dB can a moderately vigorous speaking voice of Luciano Pavarrotti, produce acoustic power of 0.100 microwatts with a room volume of 100 cubic meters, with reverberation time of 1.2 seconds?

a. 75dB b. 60dB c. 25dB d. 100dB

• It is brought about by a series of reflections between two parallel surfaces resulting to prolongation of sound.

Echo b. Reverberation c. Interference d. flutter

• One hundred twenty microbars of pressure variation is equal to

41.58 dB SPL b. 57.78 dB SPL c. 120 dB SPL d. 115.56 dB SPL

• Find the speed of sound if the temperature is 45 degrees C.

356 m/sec b. 363 m/sec c. 385 m/sec d. 405 m/sec

• Proximity effect is the microphone characteristic that results to a boost in ____ frequencies.

Bass b. Midrange c. Upper Midrange d. Treble

• As the temperature increases, the velocity of sound _______.

Increases b. Decreases c. Remains the same d. Cannot be determined

• A car horn outdoors produces a sound intensity level of 90 dB at 10 ft. away. At this distance, what is the sound power in watts?

0.12 b. 0.012 c. 12 d. 1.2

• The ______ of a sound depends upon the energy of motion imparted to the vibrating molecules of the medium transmitting the sound.

Pitch b. Loudness c. Timbre d. Intensity

• The term that describes the highness and lowness of a sound in the study of acoustics is called

Volume b. Base c. Tempo d. Pitch

• What is the equivalent sound intensity level of 2 x 10exp-12 w/sq.cm?

43 dB b. 86 dB c. 3 dB d. 6 dB

• The reverberation time of 200 cu. Ft. auditorium is 0.45 sec. Find the total absorption of the material in sabines.

72 b. 52 c. 42 d. 22

• Which of the following is the hearing range of a human ear?

1 to 4 Hz b. 10 to 100 Hz c. 10 to 100 Hz d. 1 to 4 kHz

• One sq. ft of open window is equivalent to absorption coefficient of

Unity b. Zero c. 4.7 d. 3.0

• The absorption coefficient of a person

Unity b. Zero c. 4.7 d. 3.0

• A transducer that uses a polarizing potential and depends upon capacitive variation of a corresponding potential difference.

Electrodynamic b. Electoacoustic c. Electromagnetic d. Electrostatic

• What is the typical value of the impedance of a high impedance microphone?

Greater than 500 ohms b. Below 1000 ohms c. Greater than 1000 ohms d. Below 500 ohms

• It is used to prevent the sound waves from the rear of the loudspeaker from interfering with the sound waves in front of the speaker.

Labyrinth b. Acoustic driver c. Baffle d. Phasing Device

• A type of microphone which uses the principle of variable resistance

Ceramic b. Crystal c. Dynamic d. Carbon

• This value refers to the threshold of hearing.

0 dB b. 65 dB c. 120 dB d. 200 dB

• 40 sones are equivalent to how many phons?

40 b.93.23 c. 73.2 d. 80

• The term used for the deafness of higher frequencies due to old age.

Ear deafness b. Presbycusis c. Cortial deafness d. Tinnitus

• The higher the density of the object, the _____ the velocity of sound.

Lower b. Higher c. No effect d. Cannot be determined

• Sound is considered as _____ wave because it travels in parallel with the medium.

Transverse b. Longitudinal c. Electromagnetic d. Light

• The person who pioneered the study of room acoustics.

Stephens b. Norris c. Sabine d. Bate

• What is the sound intensity for an RMS pressure of 200 Pascal?

a. 90 W/m² b. 98 W/m² c. 108 W/m² d. 88 W/m²

• A circuit that divides the frequency components into separate bands in order to have individual feeds to the different drivers.

a. Suspension system b. Dividing network c. Magnet assembly d. Panel board

Which best describe the sound wave?

a. It may be longitudinal c. It is always transverse

b. It is always longitudinal d. All of the above

Which of the following can not travel through a vacuum?

a. Electromagnetic wave b. Radio wave c. Soundwave d. Light wave

Through which medium does sound travel fastest?

a. Air b. Water c. Steel d. Mercury

Speed that is faster than that of sound.

a. Ultrasonic b. Supersonic c. Subsonic d. Transonic

What is the speed of sound in air at 20C?

a. 1087 ft/s b. 1100 ft/s c. 1126 ft/s d. 200 ft/s

Calculate a half wavelength sound for sound of 16000 Hz.

a. 35 ft b. 10 ft c. 0.035 ft d. 100 ft

The lowest frequency that a human ear can hear is

a. 5 Hz b. 20 Hz c. 30 Hz d. 20 Hz

Sound that vibrates at frequency too high for the human ear to hear (over 20 kHz)

a. Subsonic b. Ultrasonic c. Transonic d. Stereo

The frequency interval between two sounds whose frequency ratio is 10

a. Octave b. Half octave c. Third-octave d. Decade

A 16 KHz sound is how many octaves higher than a 500 Hz sound

a. 2 b. 5 c. 4 d. 8

Sound waves composed of but one frequency is a/an

a. Infra sound b. Pure tone c. Structure borne d. Residual sound

Sound wave has two main characteristics which are

a. Highness and loudness c. Tone and loudness

c. Pitch and loudness d. Rarefactions and compressions

When waves bend away from straight lines of travel, it is called

a. Reflection b. Diffraction c. Rarefaction d. Refraction

The amplitude of sound waves, the maximum displacement of each air particle, is the property which perceive as _____ of a sound

a. Pitch b. Intensity c. Loudness d. Harmonics

It is the weakest sound that average human hearing can detect.

a. SPL = 0 dB b. Threshold of hearing c. Reference pressure = 2 x 10-5N/m2 d. A, b, c

What is a device that is used to measure the hearing sensitivity of a person?

a. Audiometer b. OTDR c. SLM d. Spectrum analyzer

What is the device used in measuring sound pressure levels incorporating a microphone, amplification, filtering and a display.

a. Audiometer b. OTDR c. SLM d. Spectrum analyzer

What weighted scale in a sound level meter gives a reading that is most closely to the response of the human ear?

a. Weighted scale A b. Weighted scale B c. Weighted scale C d. Weighted scale D

For aircraft noise measurements, the weighting scale that is used is _____.

a. Weighted scale A b. Weighted scale B c. Weighted scale C d. Weighted scale D

It is the device used to calibrate an SLM?

a. Microphone b. Pistonphone c. Telephone d. Filter

_____ is the sound power measured over the area upon which is received.

a. Sound pressure b. Sound energy c. Sound intensity d. Sound pressure level

A measure of the intensity of sound in comparison to another sound intensity

a. Phon b. Decibel c. Pascal d. Watts

Calculate the sound intensity level in dB of a sound whose intensity is 0.007 W/m2.

a. 95 dB b. 91 dB c. 98 dB d. 101 dB

What is the sound pressure level for a given sound whose RMS pressure is 200/m2?

a. 200 dB b. 20 dB c. 140 dB d. 14 dB

What is the sound intensity for an RMS pressure of 200 Pascal?

a. 90 W/m2 b. 98 W/m2 c. 108 W/m2 d. 88 W/m2

The sound pressure level is increased by _____ dB if the pressure is doubled.

a. 3 b. 4 c. 5 d. 6

The sound pressure level is increased by _____ dB if the intensity is doubled.

a. 3 b. 4 c. 5 d. 6

If four identical sounds are added what is the increase in level in dB?

a. 3 b. 4 c. 5 d. 6

The transmission of sound from one room to an adjacent room, via common walls, floors or ceilings.

a. Flanking transmission b. Reflection c. Refraction d. Reverberation

_____ is the continuing presence of an audible sound after the sound source has stopped.

a. Flutter echo b. Sound concentration c. Sound shadow d. Reverberation

Required time for any sound to decay to 60 dB

a. Echo time b. Reverberation time c. Delay time d. Transient time

A room containing relatively little sound absorption

a. Dead room b. Anechoic room c. Live room d. Free-field

A room in which the walls offer essentially 100% absorption, therefore simulating free field conditions.

a. Dead room b. Anechoic room c. Live room d. Closed room

Calculate the reverberation time of the room, which has a volume of 8700 ft3 and total sound absorption 140 sabins.

a. 0.3 sec b. 3.5 sec c. 3 sec d. 0.53 sec

It is an audio transducer that converts acoustic pressure in air into its equivalent electrical impulses

a. Loudspeaker b. Amplifier c. Baffle d. Microphone

_____ is a pressure type microphone with permanent coil as a transducing element.

a. Dynamic b. Condenser c. Magnetic d. Carbon

A microphone which has an internal impedance of 25 k is _____ type.

a. High impedance b. Low impedance c. Dynamic d. Magnetic

A microphone that uses the piezoelectric effect

a. Dynamic b. Condenser c. Crystal d. Carbon

_____ is a type of loudspeaker driver with an effective diameter of 5 inches used at midrange audio frequency.

a. Tweeter b. Woofer c. Mid-range d. A or C

A loudspeaker radiates an acoustic power of 1 mW if the electrical input is 10 W. What is its rated efficiency?

a. -10 dB b. -20 dB c. -30 dB d. -40 dB

An amplifier can deliver 100 W to a loudspeaker. If the rated efficiency of the loudspeaker is -60 dB. What is the maximum intensity 300 ft from it?

a. 10 dB b. 20 dB c. 30 dB d. 40 dB

The impedance of most drivers is about _____ ohms at their resonant frequency.

a. 4 b. 6 c. 8 d. 10

It is an enclosure used to prevent front and back wave cancellation.

a. Loudspeaker b. Driver c. Baffle d. Frame

A unit of noisiness related to the perceived noise level.

a. Noy b. dB c. Sone d. Phon

100. What is the loudness level of a 1KHz tone if its intensity is 1 x 10-5W/cm2?

a. 100 phons b. 105 phons c. 110 phons d. 100 phons

With computations please. Thanks!